class_docstr: Implements an ML preprocessing operation.
  
  Preprocessors are stateful objects that can be fitted against a Dataset and used
  to transform both local data batches and distributed data. For example, a
  Normalization preprocessor may calculate the mean and stdev of a field during
  fitting, and uses these attributes to implement its normalization transform.
  
  Preprocessors can also be stateless and transform data without needed to be fitted.
  For example, a preprocessor may simply remove a column, which does not require
  any state to be fitted.
  
  If you are implementing your own Preprocessor sub-class, you should override the
  following:
  
  * ``_fit`` if your preprocessor is stateful. Otherwise, set
    ``_is_fittable=False``.
  * ``_transform_pandas`` and/or ``_transform_numpy`` for best performance,
    implement both. Otherwise, the data will be converted to the match the
    implemented method.
docstr: Fit this Preprocessor to the Dataset and then transform the Dataset.
  
  Calling it more than once will overwrite all previously fitted state:
  ``preprocessor.fit_transform(A).fit_transform(B)``
  is equivalent to ``preprocessor.fit_transform(B)``.
  
  Args:
      ds: Input Dataset.
  
  Returns:
      ray.data.Dataset: The transformed Dataset.
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code: def fit_transform(self, ds: "Dataset") -> "Dataset":
      """Fit this Preprocessor to the Dataset and then transform the Dataset.
  
      Calling it more than once will overwrite all previously fitted state:
      ``preprocessor.fit_transform(A).fit_transform(B)``
      is equivalent to ``preprocessor.fit_transform(B)``.
  
      Args:
          ds: Input Dataset.
  
      Returns:
          ray.data.Dataset: The transformed Dataset.
      """
      self.fit(ds)
      return self.transform(ds)
  
imports: import abc
  import base64
  import collections
  import pickle
  import warnings
  from enum import Enum
  from typing import TYPE_CHECKING, Any, Dict, Optional, Union
  from ray.air.util.data_batch_conversion import BatchFormat
  from ray.util.annotations import Deprecated, DeveloperAPI, PublicAPI
label_desc: Use image node_id 5 for calling the Preprocessor obj's underlying member method code with example usage: obj.fit_transform(ds) and returns: self